Image heating apparatus

Abstract

An image heating apparatus includes: a rotatable heating member; a driving mechanism; a rotatable pressing member; a first contact-and-separation mechanism; a rotatable externally-heating member; a second contact-and-separation mechanism; a detecting portion configured to detect information corresponding to a drive load exerted on the driving mechanism; and a controller configured to actuate, when the information is detected by the detecting portion, the driving mechanism for a predetermined time in a state in which the rotatable externally-heating member is press-contacted to the rotatable heating member and in which the rotatable pressing member is spaced from the rotatable heating member. The controller controls, depending on an output of the detecting portion, whether or not image heating is prohibited.

What is claimed is: 
     
         1 . An image heating apparatus comprising:
 a rotatable heating member configured to heat a toner image on a sheet at a nip;   a driving mechanism configured to drive said rotatable heating member;   a rotatable pressing member configured to form the nip in press-contact with said rotatable heating member while being rotated by rotation of said rotatable heating member;   a first contact-and-separation mechanism configured to move said rotatable pressing roller toward and away from said rotatable heating member;   a rotatable externally-heating member provided outside said rotatable heating member and configured to heat said rotatable heating member in press-contact with said rotatable heating member while being rotated by rotation of said rotatable heating member;   a second contact-and-separation mechanism configured to move said rotatable externally-heating member toward and away from said rotatable heating member;   a detecting portion configured to detect information corresponding to a drive load exerted on said driving mechanism; and   a controller configured to actuate, when the information is detected by said detecting portion, said driving mechanism for a predetermined time in a state in which said rotatable externally-heating member is press-contacted to said rotatable heating member and in which said rotatable pressing member is spaced from said rotatable heating member,   wherein said controller controls, depending on an output of said detecting portion, whether or not image heating is prohibited.   
     
     
         2 . An image heating apparatus according to  claim 1 , wherein said controller actuates said driving mechanism for the predetermined time in a state in which said rotatable externally-heating member and said rotatable pressing member are spaced from said rotatable heating member, and at the same time controls, depending on an output of said detecting portion obtained at that time, whether or not the image heating is prohibited. 
     
     
         3 . An image heating apparatus according to  claim 1 , wherein said driving mechanism includes a motor and a transmitting mechanism configured to transmit a driving force of the motor to said rotatable heating member,
 wherein the drive load is at least one of a rotational speed of said motor and a driving torque.   
     
     
         4 . An image heating apparatus according to  claim 1 , wherein pressure of said rotatable pressing member exerted on said rotatable heating member is larger than pressure of said rotatable externally-heating member exerted on said rotatable heating member. 
     
     
         5 . An image heating apparatus according to  claim 1 , further comprising:
 a cleaning mechanism configured to clean external surface of said rotatable heating member, and   a third contact-and-separation mechanism configured to move said cleaning mechanism toward and away from said rotatable heating member,   wherein said controller actuates, when the information is detected by said detecting portion, said driving mechanism for the predetermined time in a state in which said cleaning mechanism is spaced from said rotatable heating member.   
     
     
         6 . An image heating apparatus according to  claim 1 , further comprising a heater configured to heat said rotatable externally-heating member,
 wherein said controller actuates, when the information is detected by said detecting portion, said driving mechanism for the predetermined time in a state in which said heater is spaced from said rotatable heating member.   
     
     
         7 . An image heating apparatus according to  claim 1 , further comprising a bearing configured to rotatably bear said rotatable heating member. 
     
     
         8 . An image heating apparatus according to  claim 1 , wherein said rotatable externally-heating member includes an endless belt, a roller configured to rotatably support the endless belt, and a bearing configured to rotatably bear the roller. 
     
     
         9 . An image heating apparatus comprising:
 a rotatable heating member configured to heat a toner image on a sheet at a nip;   a driving mechanism configured to drive said rotatable heating member;   a rotatable pressing member configured to form the nip in press-contact with said rotatable heating member while being rotated by rotation of said rotatable heating member;   a first moving mechanism configured to move said rotatable pressing roller so that said rotatable pressing member is movable to a first position wherein said rotatable pressing member is press-contacted to said rotatable heating member and a second position where said rotatable pressing member is spaced from said rotatable heating member;   a rotatable externally-heating member provided outside said rotatable heating member and configured to heat said rotatable heating member in press-contact with said rotatable heating member while being rotated by rotation of said rotatable heating member;   a second moving mechanism configured to move said rotatable externally-heating member so that said rotatable externally-heating member is movable to a third position where said rotatable externally-heating member is press-contacted to said rotatable heating member and a fourth position where said rotatable externally-heating member is spaced from said rotatable heating member;   an executing portion configured to execute an operation in a mode in which said driving mechanism is operated for a predetermined time in a state in which said rotatable pressing member is located in the second position and in which said rotatable externally-heating member is located in the third position;   a detecting portion configured to detect information corresponding to a drive load exerted on said driving mechanism; and   a sending portion configured to send, depending on an output of said detecting portion, a signal for notifying that said externally-heating member causes abnormal rotation.   
     
     
         10 . An image heating apparatus according to  claim 9 , wherein said executing portion is capable of executing an operation in another mode in which said driving mechanism is actuated for the predetermined time in a state in which said rotatable externally-heating member and said rotatable pressing member are spaced from said rotatable heating member, and
 wherein said sending portion sends the signal depending on an output of said detecting portion obtained in each of the mode and another mode.   
     
     
         11 . An image heating apparatus according to  claim 9 , wherein said driving mechanism includes a motor and a transmitting mechanism configured to transmit a driving force of the motor to said rotatable heating member,
 wherein the drive load is at least one of a rotational speed of said motor and a driving torque.   
     
     
         12 . An image heating apparatus according to  claim 9 , wherein pressure of said rotatable pressing member exerted on said rotatable heating member is larger than pressure of said rotatable externally-heating member exerted on said rotatable heating member. 
     
     
         13 . An image heating apparatus according to  claim 9 , further comprising:
 a cleaning mechanism configured to clean external surface of said rotatable heating member, and   a third contact-and-separation mechanism configured to move said cleaning mechanism toward and away from said rotatable heating member,   wherein said executing portion places, when said executing portion executes the operation in the mode, said cleaning mechanism in a state in which said cleaning mechanism is spaced from said rotatable heating member.   
     
     
         14 . An image heating apparatus according to  claim 9 , further comprising a heater configured to heat said rotatable externally-heating member,
 wherein said controller actuates, when the information is detected by said detecting portion, said driving mechanism for the predetermined time in a state in which said heater is spaced from said rotatable heating member.   
     
     
         15 . An image heating apparatus according to  claim 9 , further comprising an operating portion configured to be provided with a key for permitting an operator to provide an instruction to execute the operation in the mode,
 wherein said executing portion executes the operation in the mode on the basis of the instruction at the operating portion.   
     
     
         16 . An image heating apparatus according to  claim 15 , wherein said operating portion displays, on the basis of a signal from said sending portion, a message for urging the operator to replace said rotatable externally-heating member. 
     
     
         17 . An image heating apparatus according to  claim 9 , further comprising a bearing configured to rotatably bear said rotatable heating member. 
     
     
         18 . An image heating apparatus according to  claim 9 , wherein said rotatable externally-heating member includes an endless belt, a roller configured to rotatably support the endless belt, and a bearing configured to rotatably bear the roller.